Spoilers for Star Wars: The Last Jedi ahead. If you thought Luke Skywalker was out of tricks, think again. In The Last Jedi, he pulls a fast one on the First Order and seemingly gets what he's wished — to peacefully pass away on the Ahch-To island. With that huge reveal, will Luke be a Force ghost in Episode 9? It seems like he's certainly planning on it.
"See you around kid," Luke says to Ben Solo (let's not dignify this punk by calling him Kylo Ren) before ending the "ForceTime" between them. After cutting himself off from the Force for so long, the effort of projecting himself so far and battling his former apprentice seems to be too great, and back on his island, the real Luke vanishes. He's always had a flair for the dramatic, and this is quite the exit.
Like Ben's namesake, Luke warns his nephew that if he strikes him down in anger, he will haunt him forever. That doesn't ultimately happen, but it seems likely that the would-be Sith will see Luke Skywalker again. Out protagonist has every intention of returning to this fight. At the very least, he'll probably also want to check in with Rey, the new Jedi hero of the resistance.
If you don't recall Revenge Of The Sith, haven't seen the prequel films, or put them out of your mind completely — the idea of a Jedi living on as wise, advice-dolling ghost was somewhat "discovered" by Qui-Gon Jinn, Liam Neeson's character in the films. He wasn't the first, but he was the first in the era in which this story takes place.
There's a small lack of continuity regarding how Force ghosts work, especially as a 2004 DVD of Return of the Jedi inserted Hayden Christensen into the 1983 film as Force ghost Anakin instead of actor Sebastian Shaw. There's also a discrepancy with what happens to the Jedi when they die. In The Phantom Menace, Qui-Gon does not disappear like Obi-Wan, Yoda, and Luke do. His corpse is cremated. But don't worry about all that too much. The Force moves in mysterious ways. What's important is that by the time The Last Jedi rolls around, Force ghosting is a pretty common practice. Makes sense, as the Jedi knights have been almost completely wiped out.
Luke Skywalker is going to join his spectral friends for sure. A Star Wars movie wouldn't deprive us of ghost Luke, right? There are a lot of unexpected moments in The Last Jedi, but this seems certain. Especially as Leia, sadly, likely won't be in the next movie due to Carrie Fisher's death. One of the original trio has to keep an eye on these kids, even if it is from beyond the grave.
There's also that surprise cameo by Yoda, of all Jedi. He appears as a Force ghost to giggle a bunch and help Luke burn down the temple with the Jedi texts. Was Obi-Wan Kenobi too busy? Yoda's brief appearance proves that Force ghosts can manipulate the physical world. That's good for Luke to know, going forward.
The more practical question to ask, in this case, is whether or not Mark Hamill will appear in Star Wars: Episode IX. Not much is known about the final film in the new trilogy, especially with the director reigns being handed from Colin Trevorrow back to J. J. Abrams, and Fisher's death affecting the plot of what would have been "her" film, story-wise. On Twitter, while shaving his beard, Hamill teased growing it back for a return in Episode IX, but that's unconfirmed. This beard is also not super relevant, as in Last Jedi, Old Man Skywalker definitely gives himself a Force makeover before going back out in public to meet with his family.
If Luke returns at all, it will most likely be as a Force ghost rather than a flashback. That much is certain. Hopefully he will be back to guide, inspire, or annoy the new Force-sensitive folk in the galaxy just a bit more. Even if Kylo Ren is irredeemable, and who knows at this point, that pesky ghost will most likely be at his side.